1. Technical Field
This invention relates in general to hard disk drive units and in particular to a system for reducing excess movement of the disks in a drive unit when it is not in use.
2. Background Art
In magnetic disk drives, the product of head load and the parking radius produces a torque known as the break away torque. The spindle motor overcomes this torque in order to proceed to other operational activities. The break away torque is a function of the number of interfaces between the head and the media, the coefficient of friction, and the parking radius. Break away torque is also affected by environmental conditions, the number of crash stop/start (CSS) cycles performed, and time. As the requirements for enduring CSS cycles increase, load-unload mechanisms for disk drives, such as ramps, are becoming more popular. Load/unload mechanisms reduce concerns of head media interaction during take-off and landing, and damage to the unit during shipping and/or handling.
However, once the break away torque is overcome, the disk pack assembly is free to move in oscillatory motions due to any disk pack imbalances and its inertia. This oscillatory motion is transmitted to the spindle motor bearing system and can damage the bearings and create higher acoustical levels in the disk pack. Thus, an apparatus and method for reducing or eliminating excessive oscillatory motion of the disks is needed.
A disk drive has a brake mechanism located adjacent to its disk pack and actuator. The brake is pivotally mounted and movable into contact with the disks and actuator. Each end of brake has a bumper for cushioning the impact between the components and enhancing friction. A spring is used to bias the brake into contact with the disks. The brake is active or locked against the disks by the spring in the absence of air flow circulation from the rotation of the disks. The brake prevents disk from rotating and excessive movement or vibration. The brake deactivates or opens as a result of the air flow generated by the rotation of the disks. The air flow is sufficient to overcome the force generated by the spring.